Supervisory signal apparatus for telephone-switchboards.



11 ,7 3, 17, r PATENTED AUG. 30, 1904.

. J. L.MOQUARRIE v SUPERVISORY SIGNAL APPARATUS, FOR TELEPHONE SWITGHBOA RDS. nrmourofirimzp JAN. 2, 1904;

N0 MODEL.

2056255 65 4 has" I '1 W729)? UNITE STAT S Patented August 30, 1904.

PATENT OFFICE.

JAMES L. MOQUARRIE, OF CHICAGO, ILLINOIS, A'SSIGNOR TO WESTERN ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A- CORPORATION OF ILLINOIS.

SUPERVISORY SIGNAL APPARATUS FOR TELEPHONE-SWITCHBOARDS.

SPECIFICATION forming part of Letters Patent N0. '7 68,617 dated August 30, 1904.

Application filed January 2,1904. Serial No. 18'7A10. (No model.)

To all whom it may concern.-

Be it known that I, JAMEs L. MOQUARRIE, a citizen of the United States,-residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Supervisory Signal Apparatus for Telephone-Switchboards, of which the following is a full, clear, concise, and exact description. I

My invention relates particularly to telephone-exchange systems of the class in which the connection-terminals or spring-jacks of the lines are constructed each with only two contact-pieces connected with the two line conductors,respectively,the connecting-plugs being correspondingly provided each with only two contacts, these forming the terminals of link conductors bywhieh lines are temporarily switched together.

The object of the invention is to provide an improved organization of apparatus and circuits for controlling the supervisory signals in systems of this character.

In accordance with my invention a supervisory-signal-controlling magnet'is provided in one of the link conductors of the plug-circuit in which a flow of current is produced during'connection with a subscribers line independent of the substation-switch. The excitation of this magnet is, however, subject to the control of another magnet in the other link conductor of the plug-circuit responsive to the substation-switch. The last-mentioned magnet may be arranged to control abranch containing a neutralizing-winding for the signal-magnet, whereby the magnet will be rendered inert during a connection, .but will be excited to display a disconnect-signal when the circuitis opened at the substation, as by the replacement. of the telephone-receiver on its switch.

I will describe my invention by reference to the accompanying drawing, which is a diagram illustrating a telephone-line extending from a substation to a central office, together with a pair of plugs and a plug circuit equipped with the improved supervisory apparatus of my invention.

The telephone-line shown in the drawing extends in two conductors 1 2 from the usual substation apparatus to the poles of a grounded central battery Z). The back contacts of the armature of a cut-off relay 0 control the connection of said conductors with the battery, and the winding of a line-relay a is included in the circuit of conducter 2 between a back contact of said cut-off relay 0 and the free pole of battery 6. Said line-relay is adapted when excited to complete a normally open local circuit 3, containing a line-signal d.

.Multiple spring-jack terminals 0 e are provided for the line on the several sections of the switchboard, each spring-jack comprising lay a is energized, the circuit of limb l to the thimbles e of the spring-jacks is completed at the front contact 0.

The operator is provided with a pair of .plugs fig and a plug-circuit for connecting lines together. Said plugs are provided with tip-contacts-f g and sleeve-contacts f g respectively. The tip and sleeve contacts of each plug are connected to the corresponding contacts of its mate by link conductors 6 7 of the cord-circuit. A battery 7) is connected in a bridge of the plug-circuit between the windings of a repeating-coil in the usual manner. Two batteries (marked 6) are shown in the drawing; but it will be understood that in accordance with the usual practice a single battery may be employed,connected as indicated.

A supervisory-signal-controlling relay it is provided having two differential windings it 71 included in parallel branches of the strand 7 of the plug-circuit. The branch 8, containing the winding [L2, is normally broken at the front contact of a relay t', included in the strand 6 of the plug-circuit, said relay being responsive to the telephone-switch of the line with which plug f may be connected. Said winding I)? when its circuit is completed by relay 1. is adapted to neutralize the effect of winding 71/, thereby rendering relay /2/ inert. Said relay when excited is arranged to close a local circuit 9. including a supervisory signal A. The windings it b may be twin wound, so that the relay will present no appreciable impedance to telephonic currents.

Supervisory apparatus similar to that just described is included in the portion of the plugcircuit between the other plug, 9, and said batmanner by removing his telephone from its switch, thereby closing the line-circuit 1 2.

The line-relay 0 thus becomes energized and completes the local circuit 3 to display the line-signal d. The operator, observing the signal, inserts plug f in the spring-jack (a of the line. This act completes circuit from the free pole of grounded battery 6 in the plugcircuit, through strand 7, ring-eontact f of plug f, thimble c of spring-jack (a, conductors 4 5, Winding of eut-ofl' relay 0, and to ground. The cut-off relay 0 is thus actuated and draws up its armatures. ren'ioving the line-signal apparatus from connection with the line. At the same time the front contact 0' of the cut-off relay is closed, thereby completing the circuit of limb 1 to the free pole of battery 6. A complete metallic circuit may now be traced from the positive pole of battery 6, through strand 6 of the plug-circuit, tip f of plug f, line-spring e of spring-jack e, limb 2 of the telephone-line, through the substation apparatus, and back over line conductor 1, contact 0 of cut-ofi' relay 0, conductor 4, thimble of spring-jack a, ring f of plug f, sleeve-strand 7,to the negative pole of battery 6. The winding of relay 21 being included in the circuit just traced, said relay becomes energized and draws up its armature, thereby closing the branch 8, including the winding k of relay it. The branch 5 forms a return-path for current from the conductor 7 independent of the telephone-switch at the substation of the line, so that a local circuit Will be provided for current through the winding it, of relay 7b as long as connection is made with the line whether the substation-telephone is in use or not. Both windings /z fi of relay /t are now included in the batteryeircuit; but the effects of the currents in these two windings neutralize one another, and the relay remains inert, thus maintaining the local circuit 9, containing the supervisory signal It, open. When upon the termination of conversation the subscriber replaces the telephone upon its switch, the circuit through the winding of relay Z is broken, thus opening the branch 8, containing the wimling a. The neutralizing eliect of winding /1 being thus removed and winding h being directly included in the circuit 7 4 5, previously traced, said relay /1. becomes excited, drawing up its armature and completing the local circuit 9, containing the supervisory signal Z. This constitutes a signal to the operator that the conversation is finished, and she thereupon takes down the connection.

Having thus described my invention, l Cltl111- 1. The combination with a telephone-line and a substation-switch controlling the linecircuit, of a connection-terminal for the line having two line-contact pieces, a pair of link conductors and a switch terminal therefor having two correspondii'ig contact pieces adapted for engagement with the said linecontacts, respectively, a source of current, a signal-controlling magnet in one of said link conductors, a branch adapted to complete a circuit for said magnet independent of the substation-switch, and means controlled by said telephone-switch for rendering said magnet inert.

2. The combination with a telephone-line and a switch at the substation thereof controlling its circuit, of a spring-jack for the line at the central ofiice, having two terminal contacts, a corresponding plug and plug-circuit for making connection therewith, a source. of current in a bridge of the plug-circuit, a supervisory-signal-controlling magnet having two differential windings in parallel branches of one of the plug-circuit conductors, a branch from the corresponding line conductor adapted to complete a local circuit independent of the substation-switch, and a supervisory relay in the other conductor of the plug-circuit, having switch-contacts arranged to control the flow of current through one of the difl'erential windings of said signal controlling magnet.

3. The combination with a telephone-line and a switch controlling its circuit, a spring jack for the line, a plug and plug-circuit, a battery in a bridge of the plug-circuit, a relay having a winding included in one strand of the plug-circuit, a branch from the corresponding line conductor adapted to complete a circuit of said battery through said winding when connection is made with a line, a subsidiary signal in a local circuit controlled by said relay, a supervisory relay included in the other strand of said cord-circuit responsive to the substation-switch, and means controlled by said supervisory relay for rendering the first-mentioned relay inert.

4. The combination with av metallic-circuit telephone-line extending from a substation to a central oliice, of a source of current in a bridge of the circuit at the central ollice, a

signal-controlling magnethaving a Winding included in one of the limbs of the line at the central oflice, a branch from said limb of the line adapted to complete a local circuit to energize said magnet, a switch at the substation controlling the circuit between the limbs of the line, a relay included in the other limb at the central oflice, and a differential Winding for said signal-magnet included in the circuit of the first-mentioned limb When the said re- IO lay is actuated, whereby the signal-controlling magnet is neutralized and rendered inert.

In Witness whereof I hereunto subscribe my name this 6th day of June, A. D. 1903. v I y JAMES L. MGQUARRIE.

Witnesses:

FRANCIS L. GILMAN. FRANCIS H. GILOHREST. 

